Most of the drawings were made with the camera. 
WILSON. 
EXPLANATION OF THE PLATES. 
The lenses referred to in 
the description of the figures, are those of Zeiss, except when the focal distance 
of the objective is given in inches. 
sevenths original size. 
Of. ce 
an. f. ¢. 
can, 
cc. mM. 
cna. W. 
(c. w.) 
CrefaGs 
cu. 
a. mem. 
deg. f. c. 
CfaiGs 
ECs (ec.) 
CC. M. 
(ec. mem.) 
ec. un. p. p. 
Wace 
SOTMGLL 
The drawings have been reduced to four- 
Common Reference Letters used in the Figures. 
Afferent canal. 
Anlage of flagellated cham- 
ber. 
Canal. 
Solid anlage of flagellated 
chamber. 
Canal wall. 
Central efferent canal. 
Cuticle. 
Dermal membrane. 
Degenerated flagellated 
chamber. 
Efferent canal. 
Ectoderm. 
\ ectodermal membrane. 
Ectoderm of unpigmented 
pole. 
Flagellated chamber. 
Solid group of formative 
cells. 
Furrow. 
Gemmule. 
Follicle of gemmule. 
Sheath of gemmule. 
Granular cell. 
Intercellular space. 
Larva. 
mes. 6. Mesoderm band. 
mes. gr. Group of mesoderm cells. 
mn.m. Multinucleate mass. 
m.p~. Peripheral mesodermic 
process. 
mes. Mesoderm (in places, mes- 
entoderm). 
os. Osculum. 
os.c. Oscular cavity. 
o. ov. Ovarian egg. 
ov. f. Follicle of ovum. 
p.w. Partition wall. 
pr.g. Problematical gemmule- 
like bodies. 
p-p. Posterior pole of larva. 
pr.th. Problematical thickenings. 
p-for. Perforation through periph- 
eral mesodermic zone. 
p.2 Peripheral mesodermic 
zone. 
pc. Paleicell: 
yr. Ridge. 
r.g. Mature gemmule. 
s.d@.c. Subdermal cavity. 
sk. Gemmule sheath. 
sup. ef.c. Superficial efferent canal. 
sp. Spicule. 
sp. p. Spicular pole. 
5. p. Surface pore. 
